1. Field of the Invention
The invention relates to a computer-implemented method for constructing and manipulating three-dimensional models of object volumes, such as anatomical parts, so as to be applicable to the simulation of surgical procedures.
2. Description of the Related Art
With the ongoing advancement in medical science, students, interns and even senior surgeons have a constant need to enrich their knowledge of surgical techniques and procedures so as to be able to provide patients with the best and most up-to-date medical services.
In the fields of osteopathy and orthopedic surgery, if surgical simulation equipment is not available to assist in the teaching and training of medical personnel, it is not possible to predict the outcome of an operation with a certain degree of accuracy or to meet the expectations of the patient undergoing the operation. Thus, the outcome of the operation depends largely on the clinical experience of the surgeon. Moreover, patients are at a high risk when undergoing an operation since the human body does not allow for a trial-and-error process. If the operation is not successful, another operation may be needed, which is, again, without certainty of success.
Teaching hospitals and some medical institutions have currently included surgical simulation as part of their curriculums or training programs. Traditionally, surgical simulations are largely limited to two-dimensional paper simulations based on X-ray images. In recent years, various two-dimensional surgical simulation visual equipment have been developed that permits input of a surgical manipulation and display of a two-dimensional image of the simulation result on a monitor. However, in the case of the human skeletal system, inview of the numerous irregular curved surfaces, it is not possible to depict the geometry of bone structures in a realistic manner by merely relying on a two-dimensional model. There are considerable visual errors when viewing the two-dimensional model on a monitor. In addition, since the surgical manipulation is limited by the two-dimensional image, and since the input information cannot fully match the surgical manipulation during an actual operation, the simulation result is expected to be imprecise and unreliable. Such a simulation model is therefore not very helpful to students and trainees as a pre-operation simulation tool, and the simulation result cannot be relied upon when predicting the outcome of an operation.
It is known in the art to use computer tomographic two-dimensional slice data for the reconstruction of three-dimensional models. A cubic voxel is generally used as a basic unit of the three-dimensional model. The known voxel records a scalar that can be used to represent material properties, such as material type and boundary. While conventional voxel data structures may be extensive for solid manipulations, they are insufficient to accurately describe the surface topology. Current surface voxelization uses continuous voxels to represent a surface. However, because the model surface is actually a solid, e.g., having a one-voxel thickness, many surface properties, such as whether the intersection between the surface and another solid is closed to form a new solid or left unclosed and dangled inside said another solid, cannot be judged after conventional surface voxelization.
Traversal algorithms are available in the art for traversing regularly positioned voxels. For instance, seed and flood algorithms can traverse all voxels inside a closed boundary, which consists of boundary voxels, so that pointers or links for neighboring solid information are unnecessary. Object flags are used to distinguish among different solids. Because seed and flood algorithms traverse a set of continuous voxels inside a closed boundary, it is hereby proposed to extend the same for manipulating a solid and for checking whether non-closed boundaries or dangling surfaces exist inside the solid.